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# Acetylcysteine
## Overview
Acetylcysteine is a mucolytic agent that breaks disulfide bonds in mucus, reducing its viscosity. It also serves as an antidote for acetaminophen overdose by replenishing hepatic glutathione stores.
## Primary Indications
* **Acetaminophen Overdose:** Treatment to prevent or reduce liver toxicity.
* **Mucolytic Agent:** For conditions with thick mucus secretions (e.g., cystic fibrosis, COPD, pneumonia).
## Adult Dosing
**Acetaminophen Overdose:**
* **Loading Dose:** 150 mg/kg intravenously (IV) over 1 hour.
* **Second Dose:** 50 mg/kg IV over 16 hours (total duration of 17 hours).
* **Subsequent Doses:** 12.5 mg/kg/hour IV for up to 72 hours if acetaminophen levels remain elevated or hepatotoxicity is evident.
* **Oral Protocol:** 140 mg/kg PO loading dose, followed by 70 mg/kg PO every 4 hours for 17 doses.
* *Note: Specific IV infusion rates depend on patient weight and recommended concentrations. Dosing may be adjusted based on acetaminophen levels and liver function tests.*
**Mucolytic Agent:**
* **Inhalation:** 1-10 mL of a 20% solution or 2-20 mL of a 10% solution nebulized every 2-6 hours.
* **Oral:** 200 mg twice daily to 600 mg three times daily.
## Pediatric Dosing
**Acetaminophen Overdose:**
* **Intravenous:** Dosing is weight-based, identical to adults (150 mg/kg IV over 1 hour, followed by 50 mg/kg IV over 16 hours).
* **Oral:** 140 mg/kg PO loading dose, followed by 70 mg/kg PO every 4 hours for 17 doses.
* *Note: For neonates and infants <1 month, use a diluted IV solution due to potential for vasodilation and hypotension.*
**Mucolytic Agent:**
* **Inhalation:**
* 1-10 years: 1-5 mL of a 20% solution or 2-10 mL of a 10% solution nebulized every 2-6 hours.
* Children < 1 year: Not well established, consult specialist.
* **Oral:** 50-100 mg twice daily to 100 mg three times daily.
## Dose Adjustments
* **Hepatic Impairment:** No specific dose adjustment, but increased monitoring is warranted due to higher risk of hepatotoxicity with acetaminophen overdose.
* **Renal Impairment:** No specific dose adjustment, but caution is advised.
## Contraindications
* Hypersensitivity to acetylcysteine or any component of the formulation.
* Asthma (relative contraindication for nebulized acetylcysteine, may precipitate bronchospasm).
## Adverse Effects
* **Common:** Nausea, vomiting, stomatitis, rhinorrhea, bronchospasm (especially with nebulized form).
* **Less Common:** Rash, pruritus, fever, anaphylactoid reactions.
* **Acetaminophen Overdose (IV):** Anaphylactoid reactions, flushing, hypotension, tachycardia, urticaria.
## Key Drug Interactions
* **Activated Charcoal:** May adsorb acetylcysteine, reducing its oral absorption. Separate administration by at least 1 hour.
* **Nitroglycerin:** May potentiate hypotensive effects.
## Monitoring
* **Acetaminophen Overdose:**
* Serum acetaminophen levels.
* Liver function tests (ALT, AST, bilirubin, INR).
* Renal function.
* Electrolytes.
* Vital signs, particularly blood pressure during IV infusion.
* **Mucolytic:**
* Respiratory status and mucus production.
* Bronchospasm.
## Clinical Pearls
* For IV acetylcysteine in acetaminophen overdose, administer the loading dose as rapidly as tolerated to achieve therapeutic levels promptly.
* Dilute IV acetylcysteine to a concentration of no more than 10 mg/mL in patients weighing >40 kg to reduce risk of anaphylactoid reactions. For smaller patients, further dilution may be necessary.
* Always have resuscitation equipment available when administering IV acetylcysteine due to the potential for anaphylactoid reactions.
* Nebulized acetylcysteine can have an unpleasant odor.
* Oral acetylcysteine can cause gastrointestinal upset; consider administration with food.
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*Disclaimer: This information is intended for clinical use and is not a substitute for professional medical advice. Always verify current prescribing information with the official drug package insert and institutional protocols.*
